Artificial Insemination in Pigs

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Artificial Insemination in Pigs

Maes Dominiek, Lpez Rodrguez Alfonso, Rijsselaere Tom,Vyt Philip and Van Soom Ann

Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, 9820 MerelbekeBelgium

1. Introduction

Artificial insemination (AI) of swine is widely practiced in countries with intensive pigproduction. In Western Europe, more than 90% of the sows have been bred by AI for morethan two decades (Gerrits et al., 2005; Vyt, 2007). When compared with natural mating, AI isa very useful tool to introduce superior genes into sow herds, with a minimal risk of disease(Maes et al., 2008). The outcome of AI largely depends on the semen quality and theinsemination procedure. In practice, fresh diluted semen for intracervical insemination ismostly used in pigs. Semen is obtained from boars on farms or from specialised AI-centres.The latter offer a diversity of breeds and genetic lines and distribute ready-to-use semendoses of constant quality to different sow herds.Three important aspects should be considered. Firstly, only semen from healthy boarsshould be used, as diseased boars may ejaculate semen that is contaminated with pathogens.

The semen from commercial AI-centres is shipped to a large number of sow farms.Contaminated semen could therefore lead to a rapid transmission of pathogens and todisease outbreaks in many different sow herds. Strict regulations and guidelines to preventdisease spreading are therefore implemented on porcine AI-centres. The second importantaspect is the fertilizing capacity of the produced semen doses. The fertilizing potential of asemen dose is inherently linked to the quality of the spermatozoa itself (Tsakmakidis et al.,2010). Examination of the ejaculates is therefore necessary. A third important aspect of AI-centres is the semen processing procedure (Waberski et al., 2008). This is not only importantto guarantee a low microbial presence but even more to obtain high quality sperm, namelyviable spermatozoa in ready-to-use semen doses that can be used for several days. Thedilution procedure and semen handling, the properties of the extender and the micro-

environment for the sperm cells influence the survival and longevity of the spermatozoa.The present chapter will review and critically discuss the different steps during the entire AIprocedure in pigs, starting from the semen collection, dilution and processing, methods andtechnologies used to assess the semen quality, the storage conditions and the characteristicsof the semen extenders that are required to maintain semen quality. A last part will focus onthe different AI strategies.

2. Collection of semen, dilution and processing

Although automated semen collection systems have been developed (Barrabes Aneas et al.,2008), semen is mostly collected by the gloved hand technique from a boar trained to mount

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Artificial Insemination in Farm Animals80

a dummy sow. Dummy sows should be solid in construction without sharp edges, andlocated in a quiet designated semen collection room with a non-slippery floor. A pre-warmed (38C) collection container is used. The top of the container is covered withcheesecloth to filter out gel portion of the semen. The end of the penis is grabbed firmly with

a gloved hand and the collection process is initiated with firm pressure to the spiral end ofpenis with the hand so that the penis cannot rotate. This process imitates the pressureapplied by the corkscrew shape of the sows vagina. Polyvinyl gloves can be used, not latexgloves as these are toxic for the semen (Ko et al., 1989). The first part of the ejaculate (pre-sperm) should be discarded. It is clear, watery fluid and does not contain sperm (~25 ml),but it may have a high bacterial count. The sperm-rich fraction should be collected (40-100ml). It is very chalky in appearance and contains 80-90% of all sperm cells in the ejaculate.Once the sperm-rich fraction is complete, the remainder of the ejaculate is again more clear,watery fluid, and should not be collected (70-300 ml). After collection, the filter with gelshould be discarded, and the collection container should be placed in warm water. Thesemen should be extended within 15 min. after collection. The ejaculation lasts up to 5 to 8

min, but may continue up to 15 min. About 100 to 300 ml of semen is collected. Semencollection from boars in AI-centres is performed approximately 2 times per week (Vyt et al.,2007).The extension process should be done in a warm room with clean and sterile equipment.The extender is added to the semen, and cold shock should be avoided by diminishing thetemperature gradually. A normal ejaculate usually contains enough sperm to inseminate 15to 25 sows using conventional AI. Each dose should contain 2-3 billion spermatozoa in 80-100 ml.

3. Semen quality assessment

3.1 Assessment of the concentration of spermatozoa in the ejaculate

The number of spermatozoa in a semen dose is important for the fertilization process. Onthe other hand, AI-centres tend to dilute the ejaculates as much as possible to maximizesemen dose production. Variation in the number of spermatozoa in an ejaculate has beendescribed between different pig breeds e.g. Landrace, Duroc and Yorkshire (Kommisrud etal., 2002), which is a first factor influencing semen dose production. Not only differences insperm number but also in sperm volume, ranging from 100 to 300 ml (Kondracki, 2003),influence sperm concentration. Individual variation within a breed is also very important(Johnson et al., 2000). Xu et al. (1998) demonstrated a difference in litter size of 0.09 to 1.88piglets when inseminating sows either with 2*109 or 3*109 spermatozoa. Differences in litter

size between both semen doses were largely dependent on individual variations betweenboars. Another study (Alm et al., 2006) using 2*109 spermatozoa per dose mentioned notonly a smaller litter size but also a lower farrowing rate at lower semen dose. In addition,several studies (Alm et al., 2006; Xu al., 1998) described lower fertility results when lowersemen doses were used in boars with suboptimal semen quality. A general guideline for thenumber of good quality spermatozoa (Table 1) in a semen dose was set at 3*109 spermatozoaper dose. According to the morphological or motility characteristics, the number ofspermatozoa should be adapted (Martin-Rillo et al., 1996). By multiplying the total volumeof the gel-free ejaculate (ml) times the sperm concentration per ml, the total sperm number iscalculated. The volume is routinely measured by weighing the ejaculate considering 1 gramequal to 1 ml and the obtained total sperm numbers is a good indicator to evaluate

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Artificial Insemination in Pigs 81

spermatogenesis (Amann, 2009).The data above clearly indicate the importance of anaccurate determination of the concentration of spermatozoa in the ejaculate.

3.1.1 Inspection of the raw ejaculate

Visual evaluation of the opacity of the ejaculate gives a rough idea on the spermconcentration. However, this method is crude and very subjective and therefore not suitablefor AI-centres with large semen production.

3.1.2 Counting chambers

Different glass chambers are described to count cells in a known volume. Haemocytometers,such as the Neubauer, Thoma and Brker chamber are reusable glass chambers with fixedvolume used for counting immobilized spermatozoa in a grit. Other reusable glass chambersas the Mackler chamber are used for assessing concentration as well as motility (Tomlinsonet al., 2001). Disposable chambers (MicrocellR, LejaR) are commonly used in Computer

Assisted Semen Analysis (CASA) since their small depth limits movement in the thirddimension (Z-axis) when the sperm path is analysed (Verstegen et al., 2002).Haemocytometers are considered as the standard method for determining spermconcentration and have a lower coefficient of variation than disposable chambers(Christensen et al., 2005; Tomlinson et al., 2001). The concentration determined by thehaemotocytometer however, was generally higher than the concentration determined usingother chambers, especially with increasing concentration. Makler chambers were describedas having higher standard deviations and more inconsistent results compared with thehaemocytometer (Christensen et al., 2005; Tomlinson et al., 2001). Disposable chambers onthe other hand, although they are also used for counting live cells, were reported to be moreconsistent and accurate (Mahmoud et al., 1997). The accuracy of different counting chambers

is also dependent on the manner in which the chamber is filled. Thin, capillary-filled,disposable chambers are generally found to underestimate sperm concentration due to theSegre-Silberberg effect (Kuster, 2005). However, the variations between chambers whenanalysing sperm concentration seems to be technician and laboratory dependent(Christensen et al., 2005).

3.1.3 Photometry

Photometers (single wavelength) or spectrophotometers (multiple wavelengths) measurethe optical density, i.e. the relative absorption and scattering of a light beam that is sentthrough a semen sample. The absorption and scattering is proportional to the spermconcentration. Next to the concentration of spermatozoa, the absorbance is also influencedby gel particles in the seminal plasma or the extender, by the quality of the sample cuvette,and the dilution of the sample (Knox, 2004). Photometry is commonly used in practicebecause it is fast and easy to perform (Woelders, 1991). Accurate dilution and a correctcalibration curve are imperative to obtain proper results.

3.1.4 Flow cytometry

Several studies use fluorescent dyes that stain intact or damaged spermatozoa differently,and measure the distribution of dyes in the sperm cell population by a flow cytometer(Christensen et al., 2004; Ericsson et al., 1993). In that way, viability as determined by thepercentage of intact cells as well as the concentration of spermatozoa in an ejaculate can be

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determined by using fluorescent microspheres. Since this technology can discriminateinterference from gel particles, it has a low coefficient of variation (3.3%) (Christensen et al.,2004). However, the high costs and the dependence on qualified personnel make flowcytometry not the most suitable method for use in practice.

3.1.5 Other methods

Coulter counters, determining the number of particles within a known volume, can be used

to assess spermatozoa concentration but discrimination of other particles with comparable

size within the sample is difficult, resulting in a lower accuracy (Woelders, 1991). Other

systems, e.g. computer assisted semen analysis (CASA) use image analysis to determine

sperm concentration within counting chambers (Prathalingam et al., 2006; Verstegen et al.,

2002). The accuracy of these systems depends not only on the optical properties and the

software settings, but also on the kind of counting chamber that is used (Kuster, 2005).

Nucleocounters are also used for determining sperm concentration, and they provide

similar counts as those obtained with photometers (Camus et al., 2011; Hnsen andHedeboe, 2003). In these devices, DNA is fluorescently labelled and counted by image

analysis resulting in an accurate determination of sperm concentration.

The concern to obtain a correct estimate of sperm concentration led to a discussion on the

accuracy of the different systems. Maes et al. (2010) did not find major differences between

two types of colorimeters, the Brker counting chamber, and the Hamilton Thorne Analyzer

(Ceros 12.1) using two Leja chambers. Every system has its advantages and limitations. They

concluded that in commercial porcine AI-centres, economic considerations such as purchase

prices, labour, and high sample throughput are also important in the choice for one method

or the other.

3.2 Morphology and viability assessment

The microscopic appearance of spermatozoa can give information on morphological

abnormalities, cell membrane integrity and the acrosome. These are three important

parameters that contribute to the fertilizing capacity of the sperm cells. Morphological

abnormalities give an indication of aberrations in the spermatogenesis. Some malformations

compromise the function of the cells and cannot be compensated for, therefore leading to

culling of the boar. Abnormal shape of the head which carries the genetic material or

abnormalities of the mitochondrial sheet which is important for the function of the flagella,

are therefore called primary abnormalities. Remainders of cytoplasm, proximal or distal

droplets, and small tail abnormalities are called secondary abnormalities and can be

compensated for by the semen dose (Donadeu, 2004). Additionally, morphologicalanomalies (e.g. coiled tails) acquired by inappropriate handling of semen are called tertiary

abnormalities.

Morphology can be assessed by staining techniques that do not require highly qualified

personnel (Shipley, 1999). Normal morphology is correlated with fertility (Alm et al., 2006; Xu.

et al., 1998), and should therefore be performed routinely in porcine AI-centres. Criteria for the

maximum percentage of primary and secondary abnormalities in commercial porcine AI-

centres were determined as 10% and 20%, respectively (Shipley, 1999). The percentage of

spermatozoa with normal morphology should be at least 70% (Shipley, 1999). An overview of

the criteria for use of porcine semen in artificial insemination is shown in Table 1.

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Semen parameter Requirement (%)

Kuster andAlthouse, 1999

Martin-Rilloet al., 1996*

Shipley,1999

Britt etal., 1999

Motility > 70 60-100 > 70 >60

Abnormal morphology < 20 < 20Normal acrosomes


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Fig. 1. Sperm morphology: spermatozoa with normal morphology, abnormal (narrow) head(primary defect) and proximal droplet (secondary defect) (arrows)

3.3 Motility assessment

Motility of spermatozoa has always been considered a primary requirement to fertilize eggs.Although the spermatozoa are brought to the fertilization site mainly by uterinecontractions (Langendijk et al., 2002), sperm motility is required for penetration of the zonapellucida. Motility is known to be an important characteristic in predicting the fertilizingpotential of an ejaculate (Gadea, 2005). Therefore, several methods have been used formotility assessment.

3.3.1 Visual motility estimation

The simplest way to evaluate sperm motility is by estimating the number of motilespermatozoa under a light microscope or using phase contrast microscopy. This method issubjective since it depends on the interpretation by an individual (Vyt et al., 2004b). It ishowever a cheap method and facilitates a high sample throughput which makes it popularin commercial AI-centres.

3.3.2 Computer assisted semen analysis (CASA)Using digital image analysis, sperm cell tracks are analysed in different components(Rijsselaere et al., 2003; Verstegen al., 2002; Vyt et al., 2004b). CASA has major advantages:the method is objective, independent of the interpretation of the technician and givesdetailed information on the sperm movement. This way, different motility patterns can beobserved, e.g. progressive movement versus hyperactivity and even differentsubpopulations of spermatozoa within an ejaculate can be demonstrated (Pea et al., 2005;Rijsselaere et al., 2005; Verstegen et al., 2002). The detailed information given by the CASA-systems renders them also very susceptible to external influences on sperm movement, suchas operator variability, semen handling and system settings are causes of inter-laboratorydifferences (Rijsselaere et al., 2003; Verstegen al., 2002). At the moment, CASA instruments

have been validated for many animal species (Holt et al., 1994, 1996; Rijsselaere et al., 2003;Wilson-Leedy and Ingermann, 2007) which makes the method available for use inveterinary practice or commercial AI-centres. The high cost of the equipment compared tothe alternative visual motility determination, is a restraint to the use of CASA in practice.

3.3.3 Sperm Quality analyzer (SQA)The SQA systems convert variations in optical density into electrical signals to determinesperm concentration and motility. These electronic signals are analyzed by the SQAsoftware algorithms and translated into sperm quality parameters. The effectiveness ofdifferent SQA systems for sperm analysis has been studied both in humans and animals,

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and different algorithms are needed for each species. A previous version of the SQA namelythe SQA-IIC was consistent and suitable for the estimation of boar semen quality. There wasa good correlation between the sperm motility index (SMI) obtained by SQA-IIC and severalCASA parameters, especially with the percentage of motile sperm and with straight line

velocity (VSL). However, the SQA-IIC is based on an old technology meant for humansperm analysis and the SMI values are based on overall information of the quality of thesperm, and do not discriminate between concentration, morphology and motilityparameters. Recently, the SQA-Vp was introduced as an SQA device specifically designedfor boars in which the sperm movement can be visualized on a screen and motility is givenas percentage of motile sperm (Lpez et al., 2011).In pigs, a motility score of 60% motile cells, independent of the method of assessment, isrequired to be considered as a fertile ejaculate (Donadeu, 2004). Above 60% motilespermatozoa, no differences in farrowing rate and litter size were recorded (Donadeu, 2004).

Apart from morphology, several attempts were made to correlate motility with fertilityoutcome. When using adequate numbers of spermatozoa per insemination dose (3*109),correlation with fertility outcome was hard to establish (Gadea al., 2004). At lower semendose, motility was well-correlated with fertility parameters. In most studies involving pigs,the predictive effect of motility was evaluated using visual motility assessment. To increasethe discriminating power of the motility estimation, objective motility assessment by CASA-measurements (Holt et al., 1997; Vyt et al., 2008) or motility of spermatozoa subjected to a

percoll gradient (Popwell and Flowers, 2004) were used. These studies found motility to bepositively correlated with fertility, especially with litter size.

3.3.4 Other sperm examination techniques

Sperm examination techniques requiring specialized knowledge and expensive equipment

are not frequently used in commercial AI-centres. They are however used for research onporcine sperm. DNA fragmentation tests can be used to identify subfertile boars, but the

study results are contradictory (Waberski et al., 2011; Boe Hansen et al., 2008). Somemetabolic responses of sperm like resistance to oxidative stress (Lpez et al., 2010) and invitro fertilisation assays are also used for research purposes. The practical relevance of these

techniques is limited due to the fact that most of the research on porcine semen is based on

the semen from good performing boars (Lpez et al., 2010). Subfertile or nonfertile boars are

rapidly culled because of economic considerations, and therefore, there is a lack ofinformation regarding sperm quality of infertile boars.

4. Storage of liquid semenFrozen storage of boar semen still yields inferior fertility due to the loss of membrane

integrity during freezing and thawing. Consequently, freshly diluted semen (liquid semen)

is widely used for AI on the day of collection or in the following days. For storage of liquid

boar semen, two factors are very important: the temperature of collection and storage, andthe composition of the storage medium (Johnson et al., 2000).

4.1 Temperature of collection, transport and storage

A different composition of the phospholipids in the membrane of boar spermatozoacompared to bull spermatozoa, a low cholesterol/phospholipid ratio and an asymmetrical

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distribution of cholesterol within the membrane render boar spermatozoa very susceptibleto cold temperatures resulting in increased permeability and loss of controlled membraneprocesses (De Leeuw et al., 1990). Hence, rapid cooling of ejaculates to 15C or coolingbelow 15C results in loss of viability or cold shock (Johnson et al., 2000). To avoid this cold

shock, prediluted ejaculates are better left at temperatures above 15C for several hours toinduce cold resistance. In practice, semen is collected in isolated cans to avoid contact withcolder surfaces and subsequent dilution is done in a manner in which temperature isdiminished gradually. Two different protocols are normally used for this purpose: 1) Onestep dilution with either preheated diluter (~33C) or diluter at room temperature or 2) atwo steps dilution with first a 1:1 dilution with preheated diluter (~33C), followed by asecond dilution in either a preheated diluter or a diluter kept at room temperature(Waberski, 2009). After the final dilution, filling of commercial doses is done and the semenis allowed to cool down gradually to 17C. When semen doses are to be transported, specialprecautions are taken to avoid temperature fluctuations (Green and Watson, 2002). Furtherstorage of diluted semen is done at 17C, at which temperature semen metabolism is

reduced (Althouse et al., 1998), a condition necessary to extend storage time.

4.2 Storage mediumThe storage media for liquid boar semen aim to prolong sperm survival, to provide energyto the cells, to buffer the pH of the suspension and to avoid the growth of bacteria (Vyt et al.,2004a). Therefore, porcine semen extenders contain ions to maintain the osmotic pressure ofthe medium, glucose as energy source, buffering systems to stabilize the pH of the extenderand EDTA and antibiotics to prevent bacterial overgrowth (Johnson et al., 2000). Thepresence of glucose as the only energy source and the low oxygen content in the recipient inwhich diluted semen is stored stimulates the glycolytic metabolism. Consequently, the

intracellular pH of spermatozoa is lowered which reduces their motility and enables them tosurvive several days at ambient temperature (Henning et al., 2009). Glucose also contributeslargely to the osmotic equilibrium. The ions in the media for liquid boar semen are merelysodium bicarbonate and sodium citrate and are simultaneously used as buffer. In BTSextender, also KCl is added to prevent the potassium loss from inside the cells, andsubsequent loss of motility due to Na-K pump inefficacy. Porcine spermatozoa are rathertolerant to minor changes in osmolality of the extender (Johnson et al., 2000). Iso-osmoticand slightly hyper-osmotic media are preferred for optimal preservation of fertilizingcapacity (Weitze, 1990). Incubation in media below 250 mOsm and above 300 mOsmrendered irreversible damage to the membranes and subsequent loss of motility.EDTA is added for its chelating properties. When Ca-ions are captured, the initiation of

capacitation is inhibited (Watson, 1995). As a consequence, the fertilizing capacity of thespermatozoa is preserved. Depending on the composition of the extender, semen can bestored for 2 to 3 days in short-term extenders and up to five days or longer in long-termextenders (Johnson et al., 2000). Long-term extenders differ from short-term extendersmainly by the use of complex buffering systems (HEPES, Tris), mostly in addition to thebicarbonate buffering system, and by the presence of Bovine Serum Albumin (BSA). Thelatter has a positive influence on sperm survival due to the absorption of metabolic bacterialproducts from the extender. Cysteine is used as a membrane stabilizer (Johnson et al., 2000)inhibiting capacitation.To prevent bacterial proliferation during storage, antibiotics are added to the extender.Bacteria originate mostly from the prepuce, thus depending on the semen collection

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technique, from semen manipulation or from the water used in the extender preparation(Althouse and Lu, 2005). Depending on the species, bacteria have deleterious effects onsemen quality, namely depressed motility, cell death and agglutination (Althouse al., 2000),either by direct effect on the spermatozoa or by acidifying the environment. European

legislation prescribes an antibiotic combination equivalent to 500 IU/ml penicillin, 500IU/ml streptomycin, 150 mg/ml lincomycin and 300 mg/ml spectinomycin, for having abroad antibacterial spectrum and activity towards leptospira. In practice most commercialextenders use aminoglycosides, especially gentamycin (Althouse and Lu, 2005; Vyt et al.,2007). However, bacterial contamination should be first minimized by good hygiene andgeneral sanitation by personnel (Althouse, 2008).The extender-concentrates are diluted in distilled or de-ionized water. Next to the bacterialquality of the water, the electrolyte content, especially the absence of calcium ions, is animportant characteristic for the water used to make the extender.The comparison of different semen extenders has been subject of two kinds of studies:studies comparing different extenders in vitro, focusing on quality of semen after storage

(De Ambrogi et al., 2006; Vyt et al., 2004a) and studies comparing fertility in vivo afterinsemination of semen stored for several days or stored in different extenders (Haugan al.,2007; Kuster and Althouse, 1999).In vitro experiments showed no differences in cell viability between short-term and long-term extenders during 9-day storage (De Ambrogi et al., 2006). Motility remainedunchanged within the first 72 hours, even in BTS-extenders, the most widely used short-term extender. Based on in vivo results, differences were noticed between different extendersbut it was not always possible to relate these differences to the type of extender. Differencesbetween long-term extenders were observed from day 4 of storage onwards (Kuster andAlthouse, 1999). The limited number of extenders compared in each study makes it difficult

to set up a ranking of the semen preserving quality of long-term semen extenders.

4.3 Storage of porcine semen in frozen stateAs mentioned above, porcine spermatozoa are particularly sensible to low temperatures andto rapid cooling due to the specific composition of the cell membrane (De Leeuw al., 1990).Cold shock can be solved technically by inducing cold resistance, namely incubating spermat ambient temperature for several hours (Watson, 1995), by contact with seminal plasmathat has a protective effect on spermatozoa (Centurion et al., 2006), together with controlledfreezing protocols. The variation in freezability of individual boars semen is however moredifficult to solve.Semen extenders for frozen boar semen are completely different from extenders for liquid

semen. The presence of egg-yolk, containing low density lipoproteins and cholesterol, has aprotective effect on sperm membrane during cooling (Bathgate et al., 2006). Cryoprotectants,especially glycerol are added in low concentration to the medium in order to diminishmembrane damage by freezing. Additionally, sugars and synthetic detergents are added,the latter having a modifying effect on the egg yolk inducing a better membrane stability ofthe cell membrane (Johnson et al., 2000). Thawing of the semen dose has been another pointof concern. Thawing has to be fast in order to maintain sperm motility and acrosomeintegrity afterwards. Both processes i.e. freezing and thawing result in plasma membranechanges, explaining the variety of protocols available.The fertility results with frozen semen have improved: cervical insemination results in a75% farrowing rate and a litter size of 9.6 (Roca et al., 2003). Nevertheless, freezing and

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thawing are time consuming processes, restricting the use of frozen semen for specificindications, such as long transport times and conservation of valuable genetic material.

5. Insemination strategies

The management of AI is very important to determine the success of the procedure and thereproductive performance of the sows. Estrus control, timing and number of inseminations,the technique of AI, semen storage on farm and the use of new AI technologies, all require aspecialized knowledge of pig reproductive physiology. The following measures could betaken to optimize the efficiency of AI on pig herds.

5.1 Boar stimuli

Correct timing of insemination requires careful detection of oestrus at regular intervals. Boarstimuli are important in promoting follicular development and expression of oestrusbehaviour (Langendijk et al., 2006). Additionally, a high level of boar stimuli increases the

frequency of uterine contractions, indicating a supportive role for passive sperm transportthrough the long uterine horns at the time of insemination. This effect can only be partiallymimicked by a robot teaser boar which emits olfactory, acoustic and visual boar cues(Gerritsen al., 2005). Increase of oxytocin concentrations in peripheral blood plasma occursin immediate response to boar presence and lasts for approximately 10 min (Langendijk etal., 2003). Therefore, exposure of sows to a boar during both back pressure testing andinsemination is crucial.

5.2 Timing of insemination

Many studies have investigated time-relationships between oestrus, ovulation, insemination

and fertilization using ultrasound testing. The key observation is that ovulation occurs at thebeginning of the last third of oestrus regardless of the overall duration of oestrus. Precise

prediction of the time of spontaneous ovulation in individual pigs has not yet beenachieved. However, prediction of oestrus duration by observing the onset of oestrus after

weaning has found broad acceptance in AI practice for calculation of the expected time of

ovulation (Weitze et al., 1994). AI should be timed as close as possible to ovulation,

preferably within 12 to 24 h before ovulation. The benefit of ultrasound testing of ovarian

morphology for pig fertility management has been shown in practice (de Jong et al., 2009).Determination of the time of ovulation in relation to oestrus behaviour and AI management

in representative numbers of sows on consecutive days has a great potential to provideshort cuts in AI timing and to develop farm-specific strategies for improvement of AI

management.

5.3 Use of new AI technologies

The development of techniques to inseminate with low numbers of spermatozoa in a smallvolume has increased insemination efficiency. This is particularly interesting when usingspermatozoa of high value that are impaired, e.g. by freezing and thawing or sex-sorting.Post-cervical or intrauterine insemination with several devices has been developed totraverse the cervix and deposit sperm in the uterine body or posterior horn of multiparoussows. Compared to standard transcervical AI, post-cervical AI allows a threefold reductionin the numbers of spermatozoa to be inseminated, whereas deep intrauterine AI allows a 5

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to 20 fold reduction (Vazquez et al., 2008). The use of post-cervical insemination variesamong and within countries. Limits may arise from the use in sows only, skills needed forcatheter handling, and the possibility of damaging cervical or uterine tissue. Semenencapsulation in a barium alginate membrane has been demonstrated to allow a single

insemination (Vigo et al., 2009). Laparoscopy offers the possibility of inseminating a verylow number of spermatozoa (i.e. 0.3 x 106) into the oviduct in anaesthetized pigs. However,the risk of polyspermic fertilization is substantial. Due to surgical intervention, its use is notappropriate in practice.

6. Conclusions

AI of swine is widely practiced and is a very useful tool to introduce superior genes intosow herds, with minimal risk for disease transmission. In practice, fresh diluted semen (3billion spermatozoa in 80-100 ml) is mostly used for intracervical insemination .The successof AI is largely determined by the semen quality and the insemination procedure. Different

parameters and techniques can be used to assess semen quality. Although more advancedtechnologies offer more accurate information, in commercial AI centres, semen quality isassessed based predominantly on concentration, morphology and motility using simple,cheap and practically easy-to-perform techniques. Critical issues for AI involve oestrusdetection in the sow, timing of insemination and applying strict hygiene measures. Futuredevelopments will focus on new technologies to better assess semen quality in practice, topreserve semen for a longer time and to inseminate sows successfully using a lower numberof spermatozoa using new AI techniques.

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Althouse, G. (2008). Sanitary procedures for the production of extended semen. Reproductionin Domestic Animals, Vol.43, pp. 374-378, ISSN 0936-6768

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Artificial Insemination in Farm Animals

Edited by Dr. Milad Manafi

ISBN 978-953-307-312-5

Hard cover, 300 pages

Publisher InTech

Published online 21, June, 2011

Published in print edition June, 2011

InTech Europe

University Campus STeP Ri

Slavka Krautzeka 83/A

51000 Rijeka, Croatia

Phone: +385 (51) 770 447

Fax: +385 (51) 686 166

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InTech China

Unit 405, Office Block, Hotel Equatorial Shanghai

No.65, Yan An Road (West), Shanghai, 200040, China

Phone: +86-21-62489820

Fax: +86-21-62489821

Artificial insemination is used instead of natural mating for reproduction purposes and its chief priority is that

the desirable characteristics of a bull or other male livestock animal can be passed on more quickly and to

more progeny than if that animal is mated with females in a natural fashion. This book contains under one

cover 16 chapters of concise, up-to-date information on artificial insemination in buffalos, ewes, pigs, swine,

sheep, goats, pigs and dogs. Cryopreservation effect on sperm quality and fertility, new method and diagnostic

test in semen analysis, management factors affecting fertility after cervical insemination, factors of non-

infectious nature affecting the fertility, fatty acids effects on reproductive performance of ruminants,

particularities of bovine artificial insemination, sperm preparation techniques and reproductive endocrinology

diseases are described. This book will explain the advantages and disadvantages of using AI, the various

methodologies used in different species, and how AI can be used to improve reproductive efficiency in farm

animals.

How to reference

In order to correctly reference this scholarly work, feel free to copy and paste the following:

Maes Dominiek, Lopez Rodriguez Alfonso, Rijsselaere Tom, Vyt Philip and Van Soom Ann (2011). Artificial

Insemination in Pigs, Artificial Insemination in Farm Animals, Dr. Milad Manafi (Ed.), ISBN: 978-953-307-312-5,

InTech, Available from: http://www.intechopen.com/books/artificial-insemination-in-farm-animals/artificial-

insemination-in-pigs

Documents

Artificial Insemination in Pigs